leaping lizards is very very good, two of my boas have come from them! very friendly and helpful, andy the owner knows his stuff and has some nice specimens in ;-) and the collection is growing all the time!
ive also dealt with snakes and adders, thats where my third boa came from, once again never had any problems with her and the price i paid for her was very reasonable!
both shops are good but offer different morphs and species so not alot of the stock is duplicated! it all depends on what you are after but due to having more experience with leaping lizards i would have to recommend them over snakes n adders